Diabetes type I is an autoimmune disease associated with T-cells and HLA factors. Insulin production decreases rapidly. Early in the disease, appropriate measures may lead to a honeymoon period during which treatment is no longer necessary. Progression to the requirement for administration of exogenous insulin is however inevitable.
The loss of endogenous control of insulin production leads to difficulties and unpredicatability in regulating the blood glucose. The main aviation safety risk relates to hypoglycaemia, with associated impaired congnition and possible coma. Brisk glycaemic variation and hyperglycaemia over 15 mmol/L can affect vision and have other deleterious functional results, including on cognition.
The diagnosis is made on the same blood glucose / HbA1c criteria as for diabetes type II (refer 3.4.4.). Age, the presence of obesity and other factors assist in determining what is the type of diabetes. Diabetes type I generally has an onset before the age of 30 and obesity if often absent. This contrasts with the commonly over 40 age for diabetes type II and the frequently found obesity.
It is sometimes difficult, at least initially, to be sure of the type of diabetes and caution must be exercised if labelling diabetes as being type II. This is particularly true for younger or lean individuals who may not [yet] require Insulin treatment but require more intense surveillance.
The aviation safety risks relate to:
Currently CAA consider the risk of hypolycaemia to be generally excessive for any form of certification.
However, the Director has issued a very small amount of Class 2 medical certificates to applicants who have demonstrated excellent glycaemic control, such that the risk of hypoglycaemia has been considered to be sufficiently low.
Restrictions and a raft of operational conditions have been imposed in such cases.